CN109565190B

CN109565190B - Electric machine comprising a stator with a uniform slot distribution

Info

Publication number: CN109565190B
Application number: CN201780046642.7A
Authority: CN
Inventors: K·E·尼特
Original assignee: BorgWarner Inc
Current assignee: BorgWarner Inc
Priority date: 2016-07-28
Filing date: 2017-07-19
Publication date: 2021-03-12
Anticipated expiration: 2037-07-19
Also published as: DE112017003791T5; WO2018022363A1; CN109478807B; CN109565203A; US10784736B2; WO2018022362A1; CN109565190A; US11018541B2; DE112017003767T5; CN109478807A; US20180034334A1; US11233436B2; US20200153305A1; CN113472103B; CN113472103A; CN109565203B; US20180034335A1; US10581292B2; WO2018022364A1; US20180034333A1

Abstract

The invention relates to a polyphase electric machine (20) having a plurality of windings (30) mounted on a stator core (28) defining a plurality of phases, wherein for each phase the windings comprise at least two parallel windings, each winding comprising a series connection of successive wire pairs (AZ, BX, CY). For each pole (1, 2, 3, 4 … … 16), the parallel winding fills one or more central slots (BB, CC) and two outer slots (AA, DD). Each winding fills each central slot by a factor of twice the factor by which the winding fills each outer slot, thereby defining between the central slot and the outer slot a ratio of 2: 1, and wherein each of the wire pairs forming the winding fills the slot at a different ratio than the slot fill ratio. The phase shifting end rings move the windings from one outer slot to another. The position changing end rings change the relative positions of the parallel windings.

Description

Electric machine comprising a stator with a uniform slot distribution

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from the following patent applications: united states provisional patent application No.62/368,070, entitled "ELECTRIC MACHINE WITH STATOR HAVING PHASE SHIFT WINDINGS (electric machine including STATOR with phase-shifted windings)" filed on 7/28/2016; united states provisional patent application No.62/368,104 entitled "ELECTRIC MACHINE WITH STATOR HAVING EVEN SLOT dispensing (electric machine including STATOR with uniform SLOT DISTRIBUTION)" filed on 7, 28.2016; and united states provisional patent application No.62/373,223, entitled "ELECTRIC MACHINE WITH STATOR WINDINGS HAVING OVER-UNDER END LOOPS (electric machine including STATOR windings with upper and lower type END rings)" filed on 8/10/2016; the disclosure of each application is incorporated herein by reference.

Technical Field

The present invention relates to an electric machine.

Background

Electric machines are used in modern vehicles for a number of different purposes. For example, electric machines are commonly used as starters, alternators, traction motors, and other applications. In these applications, the electric machine may function as a motor, a generator, or may be selectively operated as a motor or a generator.

There is an increasing demand for motors for vehicular applications as well as other non-vehicular applications with reduced size and improved efficiency.

Improvements in electric machine designs that allow cost effective manufacturing while meeting the increasingly stringent requirements of modern vehicle applications are desirable.

Disclosure of Invention

The present invention provides an electrical machine having an improved winding pattern which can be efficiently manufactured and which provides a compact and efficient electrical machine.

The present invention, in one form thereof, comprises a multi-phase electric machine including a stator operatively connected to a rotor, wherein the rotor is rotatable relative to the stator. The stator includes a stator core defining a central opening and a plurality of axially extending slots surrounding the central opening. A plurality of windings are mounted on the stator core, wherein the plurality of windings define a plurality of phases, and wherein for each phase, the plurality of windings includes at least two parallel windings, each winding including a pair of consecutive wires connected in series. For each pole, parallel windings are arranged in one or more central slots and two outer slots, the two outer slots being arranged on opposite sides of the central slot. Each winding is disposed in each central slot by the same multiple and in each outer slot by the same multiple, and wherein each winding is disposed in each central slot by twice the multiple by which the winding is disposed in each outer slot, thereby defining between the central and outer slots 2: 1, and wherein each wire of the wire pair forming the winding is disposed in a slot at a ratio different from the slot fill ratio.

In some embodiments, for each pole of the at least one winding, a first one of the outer slots is disposed on one of a clockwise side or a counterclockwise side of the central slot, a second one of the outer slots is disposed on an opposite side of the central slot, and wherein one wire of a consecutive pair of wires connected in series to form the at least one winding has a first wire and a second wire, wherein the first wire is the wire of the first and second wires that is disposed only in the first outer slot. In some embodiments, the second wire is one of the first wire and the second wire that is disposed only in the second outer groove. In some embodiments, each winding is disposed in each slot by the same multiple.

In some embodiments, the stator assembly defines a standard spacing between each pole of each phase, the standard spacing being a common circumferential spacing between respective slots of each pole, and wherein each wire includes a phase shifting end ring having a spacing that differs from the standard spacing by one slot, each winding of the parallel windings having the phase shifting end ring at the same pole position. This moves the parallel winding from one outer slot to another.

In such embodiments, the stator assembly may define oppositely disposed first and second axial ends, each winding defining leads connectable to an external circuit member, the leads disposed at the first axial end, and the phase shifting end-rings disposed at the second axial end. In still further embodiments, each wire may extend around the stator multiple times with phase shifting end rings disposed at the locations where the wires transition from one layer to another.

In some embodiments, the stator assembly defines a winding pattern in which, for each pole of each phase, a first one of the outer slots is disposed on a counterclockwise side of the central slot and a second one of the outer slots is disposed on a clockwise side of the central slot, and wherein wires disposed within one of the first and second outer slots are disposed in a radially outermost layer and wires disposed within the other of the first and second outer slots are disposed in a radially innermost layer, whereby each outer slot is filled with wires from two separate phases.

In some embodiments, each wire includes at least one position change end ring, wherein each winding of the parallel windings has one position change ring at the same position, wherein the position change end rings define a non-standard pitch, thereby changing the relative position of the parallel windings in the slots. In such embodiments, the stator assembly may define oppositely disposed first and second axial ends, each winding defining leads connectable to an external circuit member, the leads and the position changing end ring being disposed at the first axial end, the phase shifting end ring being disposed at the second axial end. In some embodiments, each phase of such a machine may include at least three windings connected in parallel.

In embodiments having at least three windings connected in parallel, some embodiments include a stator assembly having three parallel windings for each phase, wherein each pole includes two central slots and two outer slots, each central slot filled with six wire segments and each outer slot filled with three wire segments. In such an embodiment, each wire of each winding of each phase may define one phase shifting end-ring and three position changing end-rings, with all remaining end-rings defining a standard pitch. Such embodiments may include a stator assembly defining oppositely disposed first and second axial ends, each winding defining leads connectable to an external circuit member, the leads and position changing end ring being disposed at the first axial end and the phase shifting end ring being disposed at the second axial end. Such an embodiment may have a stator assembly wherein, for each pole of each phase, a first one of the outer slots is disposed on the counterclockwise side of the central slot, a second one of the outer slots is disposed on the clockwise side of the central slot, and wherein the wires disposed within one of the first and second outer slots are disposed in the radially outermost layer and the wires disposed within the other of the first and second outer slots are disposed in the radially innermost layer, whereby each outer slot is filled with wires from two separate phases. Such an embodiment may take the form of a three-phase motor.

The invention comprises, in another form thereof, a multi-phase electric machine including a stator operatively connected to a rotor, wherein the rotor is rotatable relative to the stator. The stator includes a stator core defining a central opening and a plurality of axially extending slots surrounding the central opening. A plurality of windings are mounted on the stator core, wherein the plurality of windings define a plurality of phases. For each phase, the plurality of windings comprises at least two parallel windings, each winding comprising a continuous pair of wires connected in series and filling the same number of slots. For each pole, the parallel windings fill one or more central slots, two outer slots are disposed on opposite sides of the central slot, and the number of windings in each phase is one less than the total number of central and outer slots. Each winding fills each central slot by the same factor and each outer slot by the same factor, and wherein each winding fills each central slot by twice the factor that the winding fills each outer slot, thereby defining between the central slot and the outer slot a ratio of 2: a slot fill ratio of 1. Each wire in a wire pair fills a slot at a different ratio than the slot fill ratio. Parallel windings are provided in adjacent slots, leaving an empty outer slot at each pole for each winding, with each wire extending around the stator a number of times. The stator assembly defines a standard spacing between each pole of each phase that is a common circumferential spacing between the respective slots of each pole. Each wire includes a phase shifting end ring having a pitch that differs from the standard pitch by one slot; each of the parallel windings has a phase shifting end-ring at the same pole position, whereby the phase shifting end-ring moves the parallel windings from one outer slot to another. The stator assembly defines oppositely disposed first and second axial ends, each winding defines leads connectable to an external circuit member, the leads being disposed at the first axial end, and the phase shifting end ring being disposed at the second axial end.

In such embodiments, the phase shifting end rings may be disposed at the locations where the wires transition from one layer to another. The phase shifting end ring may also define a pitch that is one slot greater than the standard pitch.

The windings of each phase may comprise at least three windings connected in parallel. In such an embodiment with three parallel windings, each pole may comprise two central slots each filled with six wire sections and two outer slots each filled with three wire sections. In some embodiments of such machines, the stator assembly may be configured such that, for each pole of each phase, a first one of the outer slots is disposed on a counterclockwise side of the central slot, a second one of the outer slots is disposed on a clockwise side of the central slot, and wherein the wires disposed within one of the first and second outer slots are disposed in a radially outermost layer, and the wires disposed within the other of the first and second outer slots are disposed in a radially innermost layer, whereby each outer slot is filled with wires from two separate phases.

Such an embodiment may take the form of a three-phase motor. It may also include a phase shifting end ring disposed at a location where the wire transitions from one layer to another and having a pitch that defines a slot that is one slot greater than the standard pitch.

The invention comprises, in another form thereof, a multi-phase electric machine including a stator operatively connected to a rotor, wherein the rotor is rotatable relative to the stator. The stator includes a stator core defining a central opening and a plurality of axially extending slots surrounding the central opening. A plurality of windings are mounted on the stator core, wherein the plurality of windings define a plurality of phases, and wherein the plurality of windings includes at least two parallel windings for each phase. Each winding comprises a pair of wires connected in series, and for each pole, the parallel windings are arranged in one or more central slots and two outer slots arranged on opposite sides of the central slot. For at least one winding, the pairs of wires forming the winding are connected in series by a reversing loop, for each pole of the at least one winding a first one of the outer slots is disposed on one of a clockwise or counterclockwise side of the central slot, a second one of the outer slots is disposed on an opposite side of the central slot, and one wire of successive pairs of wires connected by the reversing loop to form the at least one winding has a first wire and a second wire, wherein the first wire is the only wire of the first and second wires disposed in the first outer slot.

In some embodiments, the second wire is one of the first wire and the second wire that is disposed only in the second outer groove. In such an embodiment, for at least one central slot of one pole, the first wire and the second wire may be disposed in the same slot. Such an embodiment may be further configured such that for each pole, parallel windings are provided in the one or more central slots and the two outer slots, the two outer slots being provided on opposite sides of the central slot, wherein each winding is provided in each central slot by the same multiple and in each outer slot by the same multiple, and wherein each winding is provided in each central slot by twice the multiple by which the winding is provided in each outer slot, thereby defining a ratio of 2 between the central slot and the outer slot: 1, and wherein each wire of a wire pair forming one of the parallel windings is disposed in a slot at a different ratio than the slot fill ratio.

The invention comprises, in another form thereof, a multi-phase electric machine including a stator operatively connected to a rotor, wherein the rotor is rotatable relative to the stator. The stator includes a stator core defining a central opening and a plurality of axially extending slots surrounding the central opening. A plurality of windings are mounted on the stator core, wherein the plurality of windings define a plurality of phases, and wherein the plurality of windings includes at least two parallel windings for each phase. Each winding comprises a pair of wires connected in series, and for each pole, parallel windings are provided in one or more slots. A first parallel winding of the parallel windings has a second wire pair connected in series by an inverted loop, wherein the first parallel winding of the parallel windings is electrically balanced and at least one wire of the second wire pair is electrically unbalanced.

In one embodiment, the first parallel winding is disposed in one or more central slots and two outer slots disposed on opposite sides of the central slot, and wherein for each pole of the first parallel winding, a first one of the outer slots is disposed on one of a clockwise side or a counterclockwise side of the central slot and a second one of the outer slots is disposed on an opposite side of the central slot, and wherein pairs of consecutive wires connected by reverse loops to form the first parallel winding have a first wire and a second wire, wherein the first wire is the only one of the first wire and the second wire disposed in the first outer slot. In such an embodiment, the second wire may be one of the first wire and the second wire that is disposed only in the second outer groove.

In some embodiments, for each pole, parallel windings are disposed in the one or more central slots and the two outer slots disposed on opposite sides of the central slot, wherein each winding is disposed in each central slot by the same multiple and in each outer slot by the same multiple, and wherein each winding is disposed in each central slot by twice the multiple that the winding is disposed in each outer slot, thereby defining a 2 between the central slot and the outer slot: 1, and wherein each wire of a wire pair forming one of the parallel windings is disposed in a slot at a different ratio than the slot fill ratio.

Drawings

The above-mentioned and other features of this invention and the manner of attaining them will become more apparent and the invention itself will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:

fig. 1 is a partial winding diagram showing three wires defining a portion of an individual phase.

Fig. 2 is a partial winding diagram showing three wires connected in series with the wire shown in fig. 1 to form a single phase.

Fig. 3 is a top view of a stator diagram showing the arrangement of the wires of fig. 1 and 2.

Fig. 4 is a detailed view of a portion of the stator diagram of fig. 3.

FIG. 5 is another detail view of a portion of the stator graph of FIG. 3.

Fig. 6 is a cross-sectional view of the motor.

Corresponding reference characters indicate corresponding parts throughout the several views. Although the exemplification set out herein illustrates embodiments of the invention, in one form, the embodiments disclosed below are not intended to be exhaustive or to be construed as limiting the scope of the invention to the precise forms disclosed.

Detailed Description

Fig. 6 shows the motor 20. In the illustrated embodiment, the electric machine 20 is a vehicle alternator capable of operating as either a motor or a generator, however, alternative embodiments may take the form of an electric machine that may operate as only a motor or only a generator. The motor 20 includes a rotor 22 mounted on a shaft 24, both of which rotate relative to a stator 26. The stator 26 has a stator core 28 and a plurality of windings 30.

The stator core 28 may be formed from a stack of laminations and defines a plurality of slots 32. The winding 30 includes axially extending segments 34 and end turns 36 disposed within the slots 32, each end turn 36 connecting a pair of slot segments 34. The axially extending slots 32 surround a central opening 38 of the stator core 28.

The illustrated embodiment is a three-phase motor having six turns. In addition, each phase includes three windings arranged in parallel. In other words, each winding extends six times around the entire circumference of the stator core, and there are three such windings per phase. To achieve this arrangement, two separate wires or wires are used per winding, whereby a total of six separate wires or wires are used per phase. Each individual wire forms three turns around the stator and is connected in series with another wire, forming one of the three windings of each phase.

One parameter that can be used to describe the winding arrangement is the slots per pole per phase. If each such slot is filled with windings of only one phase, this is equal to the number of slots per pole in each slot group of windings. For example, in the embodiment shown, there are 18 groove segments in each groove set, each groove holding 6 groove segments, so the arrangement shown has 3 grooves per pole per phase. However, the illustrated embodiment has a so-called phase shift, and some slots hold two slot segments that are out of phase.

The use of such a phase shift may reduce the so-called skin effect. As a general rule, when conductors in a particular slot carry different phase currents, the skin effect in such conductors will be less than if all conductors in the slot carried the same phase current. While this phase shift reduces the skin effect, using this phase shift can make it more difficult to electrically balance the windings.

In order to avoid or minimize the recirculating current in the winding, a winding electrical balance is desired, especially for windings having a plurality of wires connected in parallel. Providing an electrically balanced stator can be particularly difficult if phase shifting is employed and each phase is formed by an odd number of windings arranged in parallel.

The illustrated embodiment provides a stator winding pattern that provides an electrically balanced stator with a phase shift and an odd number of windings arranged in parallel for each phase. As mentioned above, the winding pattern shown includes six turns for each phase and three separate windings. This pattern has three slots per pole per phase, but for each pole or slot group, the windings occupy four physical slots. In each slot group, there are six conductors in each of the two central slots, which conductors are all from the same phase. The two outer slots each have three conductors from one phase and three additional conductors from different phases. In order to electrically balance the stator, each slot of the slot set needs to have the same number of conductors from each of the three windings. It is also desirable that each different radial layer has the same number of conductors from each of the three windings. However, this radial balance is not as important as the balance between the slots. Exemplary winding patterns may be used to provide an electrically balanced stator and are described further below with the aid of fig. 1-5.

Fig. 1 shows three separate wires X, Y, Z connected in series with the three separate wires A, B, C shown in fig. 2. More specifically, wire a is connected in series with wire Z to form a first winding, wire B is connected in series with wire X to form a second winding, and wire C is connected in series with wire Y to form a third winding. The first, second and third windings are then connected in parallel to form one phase of the motor 20. The motor 20 is a three-phase motor and two additional phases with the same winding arrangement are also used for the motor 20.

As can be seen in fig. 3, each phase of the stator assembly defines 16 poles, each pole being formed by four physical slots. Six wires are fitted in each axially extending stator slot 32. As used herein, the radially outermost wire is in layer 1, layer 2 is the next radially inward wire position, and so on, with the radially innermost wire position being layer 6.

It can also be seen from fig. 3 and fig. 4 and 5 that each pole is formed by a set of four slots, with two central slots each being completely filled with windings (six windings in the illustrated embodiment) and only half of the two outer slots being filled with windings from a particular phase (three windings in the illustrated embodiment), thereby forming a 3-6-6-3 winding pattern. As used herein and as labeled in fig. 4, for

slots

15 and 3, starting from the outer slot on the counterclockwise side of each slot group forming a pole and moving clockwise, the slots are referred to as slots AA, BB, CC, and DD. In other words, slots BB and CC form the central slots and slots AA and DD form the outer slots.

The distance between the groove AA of one pole and the groove AA of the adjacent pole is 9 grooves. Similarly, the distance between the slots BB of one pole and the slots BB of the adjacent pole is 9 slots, and so on, the distance between the corresponding slots of the slot groups forming the adjacent poles defining the standard pitch of the machine. In the illustrated embodiment, the standard pitch is 9 slots.

Returning to fig. 1 and 2, the wire diagram marks any spacing between non-standard groove sections. The location of the numbers representing the non-standard spacing also indicates at which axial end of the stator the end rings forming the non-standard spacing are located. It should also be noted that the wire diagrams of fig. 1 and 2 also indicate in which level position the wire is located.

As can be seen most easily in fig. 3-5, the windings in slot AA are located in the radially outermost layers, i.e. layers 1, 2 and 3, while the windings in slot DD are located in the radially innermost layers, i.e. layers 4, 5 and 6. When all phases have the same pattern, the slots AA of one phase will correspond to and overlap the slots DD of the adjacent phase, allowing the outer slots to be completely filled with windings. Fig. 3-5 show windings for only one phase, except for the space between the

poles

2 and 3 of fig. 4. This portion of fig. 4 shows the position of the winding from the second phase (represented by the filled wire profile) and the position of the winding from the third phase (represented by the empty wire profile). This clearly shows how the outer slots of each phase overlap, so that each outer slot comprises windings from two different phases.

It is further noted that although the outer slots of the illustrated embodiment have windings in which the windings from one phase are all located in the radially outermost layer and the windings from the other phase are all located in the radially innermost layer, other configurations are possible. For example, windings from different phases may be alternated. In the embodiment shown this is achieved by having the windings in the slots AA in

layers

1, 3 and 5 and in the slots DD in layers 2, 4 and 6. However, this arrangement is more difficult to manufacture than the illustrated embodiment and requires a more complex winding pattern.

To control the position of the windings in the outer slots, special end rings, referred to herein as phase shifting end rings, are used. In the illustrated embodiment, each phase includes three windings connected in parallel. Each winding is formed from two continuous wires connected together at their ends to form a filament line that forms one of the parallel windings. The number of parallel windings is one less than the number of physical slots used to form each pole. Thus, for each winding or rotation of the windings around the stator core, three windings may be used to fill each of the central slots BB, CC and the outer slots AA, DD, as shown in the illustrated embodiment. By forming all three windings with a phase shifting end-ring at a particular point between the two poles (where the phase shifting end-ring is all one slot different from a standard pitch end-ring), the wire can be shifted from the three counterclockwise endmost slots of each pole to the three clockwise endmost slots of each pole, and vice versa.

For example, in FIG. 1, at the point where lines X, Y and Z transition from layer 3 to layer 4, all three end rings have 10-pitch end rings, which 10-pitch end rings serve as phase shifting end rings. In other words, after completing two wraps or turns, the wire X, Y, Z has phase shifting end rings. This can also be seen in fig. 4, where at pole 15 in layer 3, wire X is in slot AA, wire Y is in slot BB and wire Z is in slot CC, due to the 10 pitch phase shifting end rings, at pole 16 in layer 4, wire X is in slot BB, wire Y is in slot CC, and wire Z is in slot DD. In the example shown, these phase shifting end rings occur at the locations where the windings transition from layer 3 to layer 4. This is necessary to maintain a mode in which the windings are in slots AA in

layers

1, 2 and 3 and in slots DD in layers 4, 5 and 6. If an alternating pattern is used for the two different phases in the outer slots, a greater number of phase shifting end rings are required.

The wires A, B and C also have phase shifting end rings, as can be seen with reference to fig. 2 and 4. After one winding or revolution is completed, the wire A, B, C has phase shifting end rings. This can be seen in fig. 2, where the wire A, B, C transitions from layer 3 to layer 4. This can also be seen in fig. 4, where at pole 16 in layer 3, wire B is in slot AA, wire C is in slot BB and wire a is in slot CC, due to the 10 pitch phase shifting end rings, at pole 1 in layer 4, wire B is in slot BB, wire C is in slot CC, and wire a is in slot DD.

To provide an electrically balanced winding pattern, each of the parallel windings needs to be the same multiple in each central slot BB, CC and in each outer slot AA, DD. For the embodiment shown, the filling ratio between the central grooves BB, CC and the outer grooves AA, DD is 2: 1, each winding therefore needs to be arranged in the central slot twice as much as in the outer slots. This balancing is achieved using a position changing end ring that changes the relative position of the windings in the pole slots.

In the example shown, each set of wires A, B, C and X, Y, Z is subjected to a position changing end ring in order to change the relative position of the wires at three locations (for a total of six such locations). Turning first to fig. 1, 4 and 5, it can be seen that the wires X, Y and Z undergo three position changes. At the spacing between poles 8 and 9, when wires X, Y and Z are in layer 1, a set of position changing end rings are used to change the relative positions of wires X, Y and Z. At this position, the end ring wire X has a pitch of 11 slots, while for wires Y and Z, the end ring has a pitch of 8 slots. As a result, wire X moves from slot AA at pole 8 to slot CC at pole 9, wire Y moves from slot BB at pole 8 to slot AA at pole 9, and wire Z moves from slot CC at pole 8 to slot BB at pole 9.

When the wire is in layer 3, wire X, Y, Z undergoes another change in position at the spacing between poles 8 and 9. See fig. 1 and 5. The position change involves a wire X including a position change end ring having a pitch of 7 slots, a wire Y including a position change end ring having a pitch of 10 slots, and a wire Z including a position change end ring having a pitch of 10 slots. As a result, in layer 3, wire X moves from slot CC at pole 8 to slot AA at pole 9, wire Y moves from slot AA at pole 8 to slot BB at pole 9, and wire Z moves from slot BB at pole 8 to slot CC at pole 9.

As the wire moves from layer 4 to layer 5, the wire X, Y, Z undergoes a third position change at the spacing between

poles

16 and 1. See fig. 1 and 4. The position change involves a wire X including a position change end ring having a pitch of 11 slots, a wire Y including a position change end ring having a pitch of 8 slots, and a wire Z including a position change end ring having a pitch of 8 slots. Each of these repositioning end rings also moves wire X, Y, Z from layer 4 at pole 16 to layer 5 at pole 1. Thus, wire X moves from slot BB at pole 16 to slot DD at pole 1, wire Y moves from slot CC at pole 16 to slot BB at pole 1, and wire Z moves from slot DD at pole 16 to slot CC at pole 1. To provide an electrically balanced winding pattern, each of the parallel windings needs to be the same multiple in each central slot BB, the same multiple in each central slot CC, the same multiple in each outer slot AA, and the same multiple in each outer slot DD. For stators with more slots per pole per phase, the same pattern applies to the parallel wires to be electrically balanced.

The wire A, B, C is also subject to the influence of changing position end rings. More specifically and as can be seen in fig. 2 and 3, the end ring extending between the

poles

15 and 16 is a change of position end ring at the location where the wire A, B, C moves from layer 2 to layer 3. The position change involves a wire a including a position change end ring having a pitch of 11 slots, a wire B including a position change end ring having a pitch of 8 slots, and a wire C including a position change end ring having a pitch of 8 slots. Each of these repositioning end rings also moves wire A, B, C from layer 2 at pole 15 to layer 3 at pole 16. Thus, wire a moves from slot AA at pole 15 to slot CC at pole 16, wire B moves from slot BB at pole 15 to slot AA at pole 16, and wire C moves from slot CC at pole 15 to slot BB at pole 16.

The wire A, B, C undergoes a second change in position at the spacing between poles 7 and 8 in layer 4. The position change involves a wire a including a position change end ring having a pitch of 7 slots, a wire B including a position change end ring having a pitch of 10 slots, and a wire C including a position change end ring having a pitch of 10 slots. Thus, wire a moves from slot DD at pole 7 to slot BB at pole 8, wire B moves from slot BB at pole 7 to slot CC at pole 8, and wire C moves from slot CC at pole 7 to slot DD at pole 8.

Wire A, B, C undergoes a third change in position at the spacing between poles 7 and 8 in layer 6. The position change involves a wire a including a position change end ring having a pitch of 11 slots, a wire B including a position change end ring having a pitch of 8 slots, and a wire C including a position change end ring having a pitch of 8 slots. Thus, wire a moves from slot BB at pole 7 to slot DD at pole 8, wire B moves from slot CC at pole 7 to slot BB at pole 8, and wire C moves from slot DD at pole 7 to slot CC at pole 8.

As noted above, the wiring diagrams in fig. 1 and 2 mark any spacing between non-standard slot segments. The location of the numbers representing the non-standard spacing also indicates at which axial end of the stator the end rings forming the non-standard spacing are located. Fig. 1 and 2 also show from which axial end of the stator the beginning and end of the wire A, B, C, X, Y, Z extend. As can be seen in fig. 1, the position changing end rings for wire X, Y, Z are all located at the same axial ends of the stator assembly as the start and end lead ends of wire X, Y, Z, with the phase shifting end rings being located on opposite axial ends of the stator assembly. Similarly, as can be seen in fig. 2, the position changing end rings for wire A, B, C are all located at the same axial ends of the stator assembly as the start and end lead ends of wire A, B, C, with the phase shifting end rings positioned on opposite axial ends of the stator assembly. The start and end lead ends and the position changing end rings of wire A, B, C, X, Y, Z are all on the same axial end of the stator assembly, while the phase changing end rings of wire A, B, C, X, Y, Z are all on opposite sides of the stator assembly.

It is also noted that when position changing end rings are used with the wires, the individual wires having the largest pitch will extend axially further than the wires having the shorter pitch, and will have end rings that extend over the shorter pitch and end rings that are axially shorter. In other words, if three wires have position changing end rings where two wires have a pitch of 8 and the other wire has a pitch of 11, the wire with pitch 11 will extend axially further than the two wires with pitch 8 with respect to the stator core and the end rings of the wire with pitch 11 will extend over the other two wires with pitch 8, thereby avoiding spatial conflicts between the wires.

Although the described repositioning end-rings are used to electrically balance the windings, it should be noted that the wires A, B, C, X, Y, Z are not individually electrically balanced, but instead the resulting three parallel windings are electrically balanced once they are connected in pairs in series. In other words, each winding is formed by a series connection between two individual unbalanced wires to form a balanced winding. This is further discussed below with reference to tables 3 and 4.

The wires are joined together at their terminating ends. The starting end of the wire a is located in layer 1 of the pole 16, from where the wire a is wound clockwise around the core for 3 circumferences, the terminating end of which extends from the pole 15 in layer 6. The starting end of the wire Z is located in the layer 1 of the pole 1, from where the wire Z is wound clockwise around the core for 3 circumferences, the terminating end of which extends from the pole 16 in the layer 6. The terminating end of wire a is connected in series with the terminating end of wire Z by a reversing loop. The reverse loop is referred to as a reverse loop because the reverse loop connects the terminating end of the wire Z to the terminating end of the wire a, and if tracing the path of the winding formed by the pair of wires, the path of the winding is reversed at the loop. In other words, it is assumed that the current flows from the starting end of the wire Z through the series connection and terminates at the starting end of the wire a. Starting from the starting end of the wire Z, the current will flow clockwise around the core until it reaches the reversal loop. At the reverse loop, the current will reverse direction and flow counterclockwise around the core until it reaches the starting lead of wire a.

Each wire pair in the exemplary embodiment is connected to such a reversal ring. Thus, the end of wire a extending from layer 6 at pole 15 is connected in series with the end of wire Z extending from layer 6 at pole 16; the end of wire B extending from layer 6 at pole 15 is connected in series with the end of wire X extending from layer 6 at pole 16; the end of wire C extending from layer 6 at pole 15 is connected in series with the end of wire Y extending from layer 6 at pole 16. The starting lead of each wire is connected to an external circuit member. For example, the starting leads A, B and C may all be attached to a neutral connection, with the starting leads X, Y and Z all being attached to a regulator, inverter, or other circuit member. A. The starting leads of the B and C wires each extend from layer 1 of pole 16 and are conductively coupled together, and similarly the starting wires of the X, Y and Z wires each extend from layer 1 of pole 1 and are conductively coupled together. As a result, the first winding (formed by the pair of wires a and Z connected in series), the second winding (formed by the pair of wires B and X connected in series), and the third winding (formed by the pair of wires C and Y connected in series) are arranged in parallel. It should also be noted that in the illustrated embodiment, each series connection, i.e., between a and Z, between B and X, and between C and Y, is also a reverse connection, with one wire extending clockwise from the series connection around the stator and the other wire extending counterclockwise from the series connection around the stator.

As can be understood with reference to the table given below, the winding patterns described above and shown in the figures provide an electrically balanced stator assembly.

Table 1 given below provides a detailed overview of the winding pattern of wire A, B, C for the winding pattern of single phase wire X, Y, Z of three-phase motor 20.

Table 1: winding pattern of wire A, B, C

Table 2, presented below, provides a detailed overview of the winding pattern of the wire X, Y, Z for a single phase of the three-phase motor 20.

Table 2: winding pattern of wire X, Y, Z

Table 3 provides an overview of the slot locations of each wire A, B, C, X, Y, Z of a single phase of the three-phase motor 20 and illustrates how each of these individual wires is unbalanced.

Table 3: according to the total amount of grooves of the wire

	Groove AA	Groove BB	Groove CC	Groove DD
					For the total amount of A	16	16	1	15
For the total amount of B	1	31	16	0
					For the total amount of C	0	1	31	16
For the total amount of X	15	1	16	16
					For the total amount of Y	16	31	1	0
For the total amount of Z	0	16	31	1

Table 4 provides an overview of the slot locations for each of the parallel windings formed by the series connection between a pair of individual wires for a single phase of the three-phase electric machine 20. More specifically, by joining wires a and Z into a single elongate wire, by joining wires B and X into a single elongate wire, and by joining wires C and Y into a single elongate wire. Table 4 also shows that the three windings obtained are electrically balanced.

Table 4: total number of slots per winding

	Groove AA	Groove BB	Groove CC	Groove DD
					A and Z	16+0	16+16	1+31	15+1
B and X	1+15	31+1	16+16	0+16
					C and Y	0+16	1+31	31+1	16+0

As can be seen from table 4, the ratio of the central slot to the outer slot of the winding is 2: 1, however, as can be understood with reference to table 3, the ratio between the central groove and the outer groove of each wire A, B, C, X, Y, Z is not 2: 1. table 4 shows how each individual unbalanced wire is connected in series with another individual unbalanced wire to form a balanced winding.

As can also be seen from table 4, the winding formed by wire pairs C and Y is arranged such that for each pole of the winding, a first outer slot (AA or DD) is provided on one of the clockwise or counterclockwise sides of the central slot (BB and CC), a second outer slot (the other of AA or DD) is provided on the opposite side of the central slot (BB and CC), and wherein one of the successive wire pairs (C and Y) connected in series to form at least one winding has a first wire (C or Y) and a second wire (the other of C and Y), wherein the first wire is one of the first and second wires which is provided only in the first outer slot, and the second wire is one of the first and second wires which is provided only in the second outer slot. In other words, wire C is the wire of the pair that is only in slot AA (which is always on the counterclockwise side of the center slot), while wire Y is the wire of the pair that is only in slot DD (which is always on the clockwise side of the center slot).

While this invention has been described as having an exemplary design, the present invention may be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles.

Claims

1. A multi-phase electric machine (20) comprising:

a stator (26) operably coupled with the rotor (22), wherein the rotor (22) is rotatable relative to the stator (26);

the stator includes a stator core (28) defining a central opening (38) and a plurality of axially extending slots (32) surrounding the central opening;

a plurality of windings (30) mounted on a stator core (28), wherein the plurality of windings define a plurality of phases, and wherein for each phase, the plurality of windings comprise:

at least two parallel windings (30), each winding comprising a series connection of successive wire pairs (AZ, BX, CY); wherein for each pole (1, 2, 3 … … 16) the parallel windings are arranged in one or more central slots (BB, CC) and two outer slots (AA, DD) arranged on opposite sides of the central slot; each winding is provided with the same multiple in each central slot and with the same multiple in each outer slot, and wherein each winding is provided with a multiple in each central slot that is twice the multiple with which the winding is provided in each outer slot, thereby defining between the central slots (BB, CC) and the outer slots (AA, DD) a value of 2: a slot fill ratio of 1, and wherein each wire of a wire pair forming one of the parallel windings is disposed in a slot at a different ratio than the slot fill ratio;

wherein for each pole of the at least one winding (30), a first one of the outer slots (AA, DD) is disposed on one of a clockwise or counterclockwise side of the central slot, a second one of the outer slots is disposed on an opposite side of the central slot (BB, CC), and wherein one wire of a pair of consecutive wires connected in series to form the at least one winding has a first wire (C) and a second wire (Y), wherein the first wire (C) is one of the first and second wires that is disposed only in the first outer slot (DD); and is

Wherein the second wire (Y) is one of the first wire and the second wire that is disposed only in the second outer groove (AA).

2. An electric machine as claimed in claim 1, wherein each winding (30) is provided with the same multiple in each slot (AA, BB, CC, DD).

3. The electric machine of claim 1, wherein for at least one winding, the pairs of wires forming a winding are connected in series by a reversing loop, a first one of the outer slots is disposed on one of a clockwise side or a counterclockwise side of the central slot, a second one of the outer slots is disposed on an opposite side of the central slot for each pole of the at least one winding, and wherein one wire of a consecutive pair of wires connected by the reversing loop to form at least one winding has a first wire and a second wire, wherein the first wire is the wire of the first and second wires that is disposed only in the first outer slot.

4. The electric machine of claim 1, wherein a first of the parallel windings has a first pair of wires connected in series by a reverse loop, wherein the first parallel winding of the parallel windings is electrically balanced and each wire of the first pair of wires is electrically unbalanced.

5. The electric machine of any of claims 1-4, wherein the electric machine is a three-phase electric machine.

6. A multi-phase electric machine (20) comprising:

Wherein the stator assembly defines a standard spacing between each pole of each phase, the standard spacing being a common circumferential spacing between the respective slots of each pole; and wherein each wire comprises a phase shifting end-ring having a pitch that differs from the standard pitch by one slot, each winding in the parallel windings having a phase shifting end-ring at the same pole position.

7. The electric machine of claim 6 wherein the stator assembly defines oppositely disposed first and second axial ends, each winding defining leads connectable to an external circuit member, the leads being disposed at the first axial end and the phase shifting end ring being disposed at the second axial end.

8. The electric machine of claim 6, wherein each wire extends a plurality of wraps around the stator, and the phase shifting end rings are disposed at locations where the wires transition from one layer to another.

9. The electric machine of claim 6, wherein for each pole of each phase, a first one of the outer slots is disposed on a counterclockwise side of the central slot and a second one of the outer slots is disposed on a clockwise side of the central slot, and wherein the wires disposed within one of the first and second outer slots are disposed in a radially outermost layer and the wires disposed within the other of the first and second outer slots are disposed in a radially innermost layer, whereby each outer slot is filled with wires from two separate phases.

10. The electric machine of claim 6, wherein each wire comprises at least one position change end ring, wherein each winding in the parallel windings has one position change ring at the same position, wherein the position change end rings define a non-standard pitch to change the relative position of the parallel windings in the slots.

11. The electric machine of claim 10 wherein the stator assembly defines oppositely disposed first and second axial ends, each winding defining leads connectable to the external circuit member, the leads and the position changing end ring being disposed at the first axial end and the phase shifting end ring being disposed at the second axial end.

12. The electric machine of claim 10 wherein each phase comprises at least three windings connected in parallel.

13. The electric machine of claim 12 wherein each phase comprises three parallel windings and each pole comprises two central slots and two outer slots, each central slot filled with six wire segments and each outer slot filled with three wire segments.

14. The electric machine of claim 13, wherein each wire of each winding of each phase defines one phase shifting end ring and three position changing end rings, all remaining end rings defining a standard pitch.

15. The electric machine of claim 14 wherein the stator assembly defines oppositely disposed first and second axial ends, each winding defining leads connectable to the external circuit member, the leads and the position changing end ring being disposed at the first axial end and the phase shifting end ring being disposed at the second axial end.

16. The electric machine of claim 15, wherein for each pole of each phase, the wires disposed within one of the first and second outer slots are disposed in a radially outermost layer and the wires disposed within the other of the first and second outer slots are disposed in a radially innermost layer, whereby each outer slot is filled with wires from two separate phases.

17. The electric machine according to any of claims 6-16, wherein the electric machine is a three-phase electric machine.